Detection circuit



Oct. 3, 1961 I Filed July 19, 1957 i V. HECHLER IV DETECTION CIRCUIT 2 Sheets-Sheet 1 mvsmox 1 Valentine "Hechler, H

Oct. 3, 1961 v. HECHLER |v 3,003,033

DETECTION CIRCUIT Filed July 19, 1957 2 Sheets-Sheet 2 INVENTOR. Valentine Hechler, 1y

Valentine Heckler IV, Evanston, Ill,

that occur in an external situation to DETECTION CIRCUIT or to Webs,

ration of Illinois I. No. 672,997

This invention relates, to a detection circuit, and more particularly to a circuitcharacterized by its production of a pulse upon the'occurrence of an-int'erruption in the normal condition thereof through interrupter means responsive to achange in an externalsituationtohedetected bythe circuit. The circuit may be employed, for example, for energizinga counter to indicate: the number from-aconveyor, and to controlmove- I h no. s

Filed July 19, 1951,

1 Clalm- (CI.

of articles passing ment of the articles;

The specific embodiment i'of" inventioniistobe described in detail herein isshown in the exemplary environment of an article dispenser, and its function is that of providing an accurate control of the articles discharged by the dispensing appara't s and in someenyironments where it is necessary to havean absolutely accurate indication of the number of articles being dispensed it provides for this also,such as where the dispensing apparatus might be shut off prematurely permitted to run for an excessive time, or perhaps not started into operation following a period of interruption in a sequential operating cyc e. h,

i A need thenexists for an improved detection circuit, and it is accordingly an object of thisinvention to provide such an improved circuit. Another. object of the invention is that of providing a not produce false counts, and which to provideaccurate indications of the is functional then be detected by. the circuit. Still another object is in the provision of a circuit equipped with an'interrupter means which areref Un d i s Pat n v 12, and at their forward ends,

Patented Oct. 3,

FIG. 2 is a schematic diagram of a circuit embodying the invention;

FIG. 3 is a schematic diagram of a modified circuit;

and

FIG. 4 is a schematic diagram of a count divider cir-. cuit triggered by pulses generated in either of the circuits shown in FIGS. 2 and 3.

To facilitate adescription of the circuit that comprises an embodiment of the invention, it is shown in conjunction with a conveyor which will first be described. The conveyor may take varied forms, and the conveyor mechanism per se is not herein considered an inventive feature.

The specific illustration comprises a frame having substantiallyparallel rails or supports 10 and 11 which may be equipped with a plurality of depending support legs arewrigidly secured to a panels 14 joined depending from pane 13 and side rigid with the front thereto, Preferably, a top panel 15 is and the side panels and with the rails provided with spaced; apart, parallel slots or recesses 16 -'Ihese slots pass the respective endless conveyor belts 18 and 19 therethrough which are entrained adjacent the slots 16 and 17 about a drive roller 20, and are preferably supported intermediate the ends of the rails 10 and 11 by spaced apart rollers 2.1 which are re tablyxjournalled at the respective ends thereof in the rails'10' and 11.gi

detectioncircuit that will number of changes 7 sponsive to changes that occur in an environment external of the circuit and whichfunction to interrupt the normal condition of the circuit, whereupon it produces a pulse or current surge that may be used to provide an indication or count of suchchanges.

shows a' carton v conveyor-structure and below the cover platev ISthereof,

Theendless belts 18 and 19 travel in the direction of the arrows, or toward the left in FIG. 1, and are adapted to carry articles such as the packages or cartons to the forward discharge end ofthe conveyor. Such;cartons in passing from the endsof the conveyor bel travel over a swi ,h 23 to actuatethe same. As willbe brought out more fully hereinafter, the switch 23h normally closed and may be carried by the top plate 15of the conveyor structure. ,Itwill be noted that FIG. 1 22 adjacent the front panel 13'of the andTsuch carton has actuated the switch 23 inmoving b M, s The drive roller 20-may be equipped at one end thereof .entrainedl Yet another object is toprovide a circuit having a voltage doubler andfeed-back network which functions through portions of the circuit following an interruption in the, normal condition thereof, 7 such current surge beingrepresentative therefore of the 1 i change in" the normal condition thereof. A further object is to provide a circuit of the character described,

wherein the feed-back is counterbalanced at predeter-E the normal condition of the circuit is mined times when disturbed or interrupted, whereby there. surge or pulse to indicate such disturbance, ture is of importance for preventing false counts.

Yeta further objectof invention is in the provision of apulse circuit having a normally closed switch ina feed-back branch thereof which is, adapted to be positioned adjacent an end of a dispenser (a conveyor, for example), and to be opened each time an article passes thereover-'-such switch performing the function of an interrupterfor the circuit hich functions, following each normal interruption, to produce a current surge utilizable in energizing a counter'anda' visual indicatorwhereby the passage'of each article is no current .veyor.as an environmental settingwith which the inven- -tionmayheus d;- "1 a 1 I from the d1s- "penser is made known. Additional objects nd advanand this fea- :to the illustrated position with a sprocket M having adrive chain 25 lthereabout, which. at its? opposite end is entrained about a drive sprocket rotatablydriven by a motor 27. 'It

- .will beappreciated from, whatghas been said, that the conveyor'de'scn'bedis to be considered exemplary only and may,of course, be substantially altered in mm.

Referring now to the circuit illustration of FIGPZ, it will be seen and isfshown'in its normally closed position. To the left, of switch is va relay or solenoid having contacts 29 which are adapted to be'connected to the motor 27 for energizing the same. That is to say, one side of the contacts 29 may be connected to a power source, as through the line 30; and the other side thereof connectedto the motor 27 through the line 31. Therefore,

when the solenoid28 is energized, power is suppliedto the motor 21 throughthe contacts 29, and the conveyor will then be actuated. 1 t

The solenoid 28 is shown in dotted lines for it is only incidentally relatedto the, detection circuit and may in certain instances, asshown in the drawing, be venergized when power is supplied tothe circuit. Both the relay 28 .and switch 23 are seen to'have one side thereof connected to a common line 32 which maybe thought of as the power source, although in 'thefillustration the line 32 is connected to a source of DC. 1 voltage through a switch 33. It should intended to be exemplary of any type of'connector means 10 and 11, and is fromthe ends of the conveyor i that the switch 23 is schematically illustrated be noted that while the-switchis 7 shown as a conventional on-ofl switch, such showingii's 3 circuit to a power source, and will ordinarily be .a pair of contacts of a control relay. The specific embodiment of the circuit illustrated is adapted for use with a 28-volt D.C,"po'Wer source. V f 1 f Shown connected in parallel with each other are contrc-land. indicating devices 34 and 35', hereinafter generally referred to as indicia devices, and a unidirectional current flow device 36, .Each of these devices has one side thereof connectedto the common line '32. The indicia device 34 could be an electronic or magneticcounter. In the representation shown, it is illustrated inthe form of 'afrel'aydevi'ce providing 'a resistance work load and adapted to be energized when a current of predetermined magnitude or pulse characteristic flows .therethrough. Theswitch contacts (not shown) of this solenoid may be connected in circuit with a counterin :a manner such that the counter circuit is actuated when the solenoid, is energized, whereupon the counter registers such condition of energization. 'The indicia device 35 is shown he a light and, therefore, provides a visual indication of flow of current therethrough having sufficient magnitude to energize the same. I Theuni-directional current flow device 36 is a rectifier and may be of the semi-conductor, junction type which is suitable for handling the relatively "large current surges that flow in the circuit. It is apparent that the input side of the rectifier 36 is connected to the positive or common line 32, and its resistance is extremely low when compared to that of the devices 34 and35 so that current will fiow therethrough to the "almost complete exclusion of -,curr'ent'flow through 'the parallel devices 34 and '35 when the, direction of current flow "is such "as "to be passed by the rectifier. I g I e I fl'hefline of common connection between the relay 3'4, glig t 35 'and'rectifier 36 is designated'with the numeral "37, and connected thereto is a 'capacitance38 having a relatively large value, which in thisparticular 'cir cuiternodiment'is 'in'the order of "about llldmicrofar'ads. The :capacitance'3 8 isgrounded through a 'chargingresistanc'e 39, andit is apparent that onesid e of theswitch '23'is lcjcinnected to the common pointjbetw'een theserially connected capacitor and charging'resistanc'e. V

The components thus far described constitute the es- ,sential elements of the detection circuit exemplifying-the present invention, However, such circuit "embodiment j ay be used in conjunction with a, pulse'transmitting net- "work, 'th'atjmaintains operative readiness free of "anyfexjcursions occurringin thejcircuit otherthan desired pulses, w. 1 1' hcomprises a resistance 40, on'e si'deot whichis connecteddirectly to a 28- voltfpower'sonreeand the other side of which is 'connected'to a resistance 41f2ll1Cl'COli1- firnonly therewith tothe outputjside of a rectifier '44 which has minimum resistance to :current flowin the direction indicated in the ra e. .The'rectifier mayibe conductor, junction typerectifier, and itsc'athodecr'input side is connectedto the line 37. The rectifier 44 prevents the source voltage through resistance from appearing on the line 37 and it receives and transmits pulses that have a value above the source voltage when such pulses are present in the line 37. The pulse output from this circuit appears at lead 45' and, as indicated" in 'FIG. 2, the lead 45 may be divided into two 'po'ints of ,connection 1 and I which are connected to a'counter circuit, as hereinafter described. I e H Y e V H In describing the operation of the circuitpassunie for convenience a condition in which switch 33*is closedand 'janiarticle 22 is resting onjthe switch 23. Atthis'time,

the switch 23 will be open and the capacitor'38 'is charged through rectifier 36 to a plus voltage potential of 28 volts with the other side thereof elfectively grounded at zero ',voltage by resistor 39. Neither the relay'34 nor the light 35 will have, been energized since any flow of charging current to the capacitor will have been through rectifier 36.

"Now then, when the article 22 is passed from enagethereof. Such nent the switch 23 and may be, for example, in the position 22b illustrated in FIG. 1, the switch will return to its normally closed condition and therefore forms a short circuit across the serially connected relay 34 and capacitor 38, and places :a potential of 28 volts on the ground side of the capacitor. Under thiscondition, the resistor 39 prevents a full short to ground, and is selected to have the lowest value possible compatible with nonexcessive current drain. It is apparent that since the capacitor already has a charge of 28 volts thereacross, an efiecti-ve potential of 56 volts is now present at the positiveside of the capacitor--that is, on the line 37. The result of this is that the capacitor attempts by reverse current flow to discharge, and being blocked by the rectitier 3-6 ca-tlsesa current flow through the energizing coil of the relay 34 and through thelight 35. This blocking by :the rectifier occurs because of, its uni-directional current flow characteristic. The'magnitude of the current surge is sufficient to energize the relay34, whereupon control can be etiected and the-counting device actuated; and, to energize alsothelight 35, wherebya visual indication of such current flow is provided. The size of the capacitor :38 is related to the load carried by its discharge, but in the embodiment shown is mi. In other electronic circuits, the value 'couldbe as low as .1 mt, for example or much higher than 100 mf. if desired. Ihe bigger the capacitor, the longer the current how is sustained.

The relay 34 and :light35 will remain energized an appreciable time before the capacitor is discharged to the fallout current value of the relay. The circuit will then be returned, to its original condition when the switch 23 is again opened by a package. Thereafter the cycle is "repeated beginning with .acharging of the capacitor 38 to a voltage :diiierential as already described through the rectifier 36. Whenthe switch 23 is closed, the capacitor discharges as:described,-toenergize theindicia devices 34 and .35 andregist'er :another count and visual'indication cyclic operation is continued so long as the conveyor :mechanism is actuated and cartons or articles 22 pass overthe-switch- 23.

"It will be appreciated that the circuit functions as a voltage doubler and pulsegnerating network in that it "periodically develops an effective56 volts on the line 37 to generate a current utilized in the embodiment shown asa pulse of predetermined duration.

It will be notedfrom the foregoing description that the'circuitis operativetosenseor detccta change in a c ondition external thereof, andin the specific environrnentalsettingfunctions to provide a determination of thepassage of articles '22*from the end of theconveyor apparatus, Attention should be directed to the fact that lan'gindic ationof-the discharge of an article from the conveyor'is provided only after anarticle has passed com pletely over the switch 23. This consideration is of 'importan ce in the'feature of the circuit which prevents false counts. In'this respect, consider first a condition wherein the conveyoris deactuated with an article 22 resting on the switch '23 whereupon it is open. The circuit will, of course, provide no indication of the presence of the article on thc-switch'before the conveyor action 'is terminated. Now, 'ifthe conveyor is reactuated, the capacitor 38 immediatelycharges, and the charging rate :is rapid becauseof the low r siistance'of the resistor 39. Consequently, when the operation of theconveyor now :inoves the article from the switch causing it to return torits normally, closed condition, the capacitor discharges and therefore causes a register of the passing of the article from the conveyor.

Consider on the other hand, a conditionthat-isprone to cause false counts in prior art devices, and that is when the-apparatus is deactuated with the detector switch "23 thereof'normally closed. If the operation of the con- V cyor is characterized by cyclic startingand stopping, especially of an irregular manner and where the stops are can (amass wa p b t n present circuit obviates I pulse that energizes the 111C135.

, tenance of a current the set elfect is substantially the smells if the detector switch hadbeen opened and closed, and it will be apparent ofcourse'result in false counts. The this disadvantage in that it ignores any position; that the switch 23 may happen to be in when theconveyo'r is first actuated; and even though the switch is closed and the remaining circuit therethrough is in operative condition, one package must pass over the switch before any pulse of any nature is actually generated to energize the counter relay 34 and light'35. This does'not mean, however, that there may not be some voltagesfappear atthecapacitor, but rather that any voltages that do appear are initially counter-balanced uponclo'sure of switch, andsuch counterbalance is overftheswitch 23 which",-*as' has; been stated, results in indicia devices 34 circuitry, as has been brought out before,

andQshapes useful pulses in accordance with the currentsurges that energize the indicia devices 34 and 35, and such useful pulses may be employed in a variety of applications as, for example, in triggering dividing circuits, as additionally described hereinafter.

The circuit of FIG. 2 is essentially a current utilization circuit, and depends for its success on the mainflow through the relay 34 even though the voltage across the relay, 'or across the relay and .thecapacitance 38 andresistance 39 connected in series therewith, changes. I For example, the voltage at the endpoints of therelay 34 shifts in that the voltage atthe upperend thereof is either zero depending upon the position offlthe switch 33; and the voltage at the lower end thereof is zero when the switch 33 is open, is 28 volts when the switches 23 and 33 are closed, and is thereafter momentarily 56 volts when the switch 23"has been opened. After this latter condition, when switch 33 is opened the voltage at line 37 immediately drops to zero. Current nevertheless continues to through the relay 34 and through the indicia device 35, thereby givingthe requisite signals until the capacitor 38 is discharged or switch 23 is opened.

In some instances, it may be desirable to elcminate th'relay 34 and transistorize'the circuit. In such event, it is advisable to utilize changes involtage appearing on the line 37'or, more specifically, at the point of con- :nection between the resistance 40 and rectifier '44. How- -ever,as explained above, the voltage at this point immediately decays to zero when the switch 33 is opened. *Consequently, a modified typeof circuit would then be "neces ary w "ea would function to hold and store for a relatively long time the pulses that appear at this point.

, The circuit of FIG. 3 includes a substantial number r or elements utilized in the FIG. 2 circuit, and for conafter 7 one package fadvances "completely or +28 volts ,7

A counter switch Zita-is the source voltage to the bottom.

i The capacitors 3 8a and-46arepreferably of substantially the samevalue'and may be,'for example, about .1

mi The resistance '47 is relatively small and may have a 'Y'Such a circuit is illustrated FIG. 3, and it will now smear-me capacitor 38d which is groundedthrough the resistance 39a. Newly added to the circuitlarea capacfitor 46, and resistance 47 that connects one side of the capacitor ,to the source voltage th ough a The opposi side. of the capacitor. is grounded. 37a has the rectifier 44a therein, side of the capacitor 38a to the point of common connection between the resistance .47 and rec 'fier 36a, and also to the output line define two points of connection I; and 1,.

i Line .70 and connects the upper,

power source is grounded and value of about 100,.o The value of the resistance 34a is selected so as to have a value that is less than the load resistance coupled to the output line 48. For example, the resistance 34a mayhave a value of about SK when the load resistance is about .5 megohms. It should be understood, however, that the load resistance maybe selected and varied so as to time is most appropriate for the capacitance 46, and to thereby determine the length of the pulse appearing on the line 48 and which will be utilized to trigger or actuate the subsequent circuits.

When the switch 334 is closed and switch 23a isopen, the capacitance 38a charge to a value of 28 volts assuming that that is the, value of the source voltage; and similarly, the capacitance 46will charge to. the same value, through the rectifier af-package. leaves the switch 23a'so bottom side of the capacitor to the source potential and'the value of the. voltage up pearing at theline 37a is 56 volts, as heretofore described in connection with the "embodiment shqw n in FIG. 2. Almost instantaneously, because of the polarization-of the rectifier 44a and small value of thefrcsistance 47 the charge differential appearing on the upper sides of the capacitors 38a and 46 tends to equalize, whereupon the 5 6 volts appearingron the upper side of the capacitor 38a is reduced to a value of 42 volts, and that'appearing at the upper side of the capacitance:46 increases to 42 volts,

It will be apparent that the respective decrease and increase of the voltages is in The rate of discharge of the capacitor 46 be dependent upon thefvalueofthe resistance load through which it must discharge; "andthus is substantiallyiindependent of the remaining circuit elements for its path of discharge can only be through the line 48 since the rectifiers 36a and 44a block the. flow of current in any other direction. Consequently, byrvarying the value of the resistance load, the duration of 14-volt pulse present on the output line 48can'bemade'as long or as shortas desired,: Itis apparentthen that the circuit of FIG. 3 provides voltage pulses atthe output 48 ,which may be utilized by subsequent circuitry independently of the discharge current from the capacitance 38a, and is thus distinguished from the circuit of FIG. 2 which depended for its functioningauponthe discharge current from the capacitor 38.

The outputpulsesfrom'either the circuit of FIG. 2 or that of FIG. 3 may be used to trigger or actuate subsequent circuits as, for example, the divider circuit shown in FIG. 4 which is essentially a flip-flop or gate circuit depending upon whether the inputs 1; and I, are tied together. This circuit is used with a power source defined by lines 49 and 50; and since the voltage at the line' '50 is of negative value,'the positive side or such comprises, line 49. The source voltage may have a value of about ,-'-20 volts.

Thecircuit comprises a pair of transistors 51 and52 having the respective emitters together and connected to ground 49 through a resistance 55. The collectors 56 and'STof the respective transistors.

59 The base 60 of transistor resistance 61, and is also connected to input I through 48 which may be divided so as to s rectifier 62 and capacitor 63. In a similar manner,the

base64 of transistor 52 is grounded through resistance 65, I

define whatever discharge 7 36a and resistance. When as to close it, the 38a is immediately brought the value of 14 volts which is one-half the 28-volt increase which appeared on the upper 53 and 54 thereof tied i and is connected to input 1- 'ithrou'gh rectifier 66 and capacitance 67. 3 minus voltage is applied to each of the respective bases '60 and 64 through the dropping resistors 68 and 69 which may be connected thereto through the rectifier-s and, "if desired, through the load resistors 58 and 59.

The collector 56 is tied to base 64 of the transistor 52 through resistor 70, and in a corresponding manner, the collector 57 is tied to the base till of transistor 5i through resistor 71. Also, the respective bases 60 and 64 may be additionally connected to B minus through resistors 72 and 73 and capacitors 74 and 75, respectively connected in series with such resistors. The output of the divider circuit appears on the lines so and 77, respectively connected to the collector '56 and transistor 51 and collector 57 and transistor 52. The circuit has two stable states, in one of which the transistor 51 conducts and the transistor 52 is cut oii, and vice versa. The state of the circuit can be shifted from one to the other of these conditions by the application of appropriate input pulses thereto. q i

In describing the operation ofthe circuit, assume first that the transistor 51 is conducting and the transistor 52 consequently is cut off. In this condition, the voltage appearing at thebutput '76 will be about -5 volts, while that appearing-attire output 77 will approximate the B minus voltage and will be, for example, between about -15 to -20 volts. Also then, the voltage appearing between the capacitor 63 and'rectifier 62 will be about -5 volts, and thisconditionof'the circuit will continue until appropriate input pulses are applied at I Ani'nput pulse or signalapplied at I in order to change the state of the circuit, must .be of greater magnitude than the voltage (-15 volts) present at the point of con nection between the capacitance 63 andrectifier 62-. 1A changein voltage in-thenegative direction will notalter the conducting-state of the circuit, and neither will a change in'voltage that'is not greater than the potential on the base of "transistor '51. We know .froni'the prior description that the value of the output pulse at the output line of the circuit of PEG. 2 comprises a change in the positive direction of approximately 28 volts; and with thecir cuit ofFlG. 3, the change in'voltage appearing at the output line 48 is in the positive direction and has a value of approximately "14 volts. Since both of these-voltage values are in the proper direction, and in magnitude exceed the value of the voltage appearing at the cathode of the rectifier 62, each will be "effective to drive the base 6t} of the transistor 51 positive whereupon it will be cut off. The voltage on the collector of this transistor will immediately rise toward the B minus value, and the voltage then caused to appear on the'output line 76 will change from 5 volts to about -15 to -20 volts. I

The base 64 of the transistor '52 will now be biased more negatively because of the application of the increased negativ'evoltage applied thereto through the resistance 70 from the collector 56 of transistor 51, and transistor '52 will begin to conduct. The voltage appearing at the collector thereof will drop to some value much lower than the B minus voltage, and then the output. line 77 will have avoltage of about -5 volts appearing thereon. This condition of the circuit will now be maintained until another pulse is received from the circuits of FIGS. 2 or 3 which, if coupled to I will cause'the transistor 52 to be cut oil in the same manner as heretofore described in connection with the transistor 51, and the tranl sistor 51 will again begin to conduct;

It is contemplated that a'number of circuits of the type ishown in FIG. 4 willbe connected in a sequential network-and will serve to divide the sum of the pulses generated'by the circuits of FIGS. and f5, vEach.divid r. circuit of the type shown iniFIG.-4-wi1l divide by two so that if two such circuits are connected in a network. the output of the last will be one-.fourthithc number of pulses generated by the circuits of FIGS. land 3. The reason ,for this is evident in that to trigger the circuit; it is necessary to .have a pulse that exceeds in magnitude in a positive direction the voltage value on the base of the transistor which is most positively biased at any time... As a result, a change in voltage on the line 76. from -5 to -15 volts will not trigger asuhsequent circuitjor it is; a change in the negative direction. However, the change in value from 15 to -5 volts appearing on the line 77 would be a change in the proper direction-land of sulficient magnitude totrigger a subsequent dividing circuit. Therefore, if either of the outputs 76.01 77 is considered, his necessary for two pulses to be received by the circuit of FIG. 4 in order to obtains-change on eitherof-gtheseoutput lines ofiproper character to trigger another icircuit connected thereto. Y

One of the important advantages of the circuit off-1G. 4 is that .it is not necessaryto have .a positive voltageto trigger itthat is, .to cause it to .flipirom .one stable position to another. As a result, itis possible to makepositive voltages where no positive voltages exist anywhere in the circuit, and this is accomplished .rigl1 t within the circuit itself. Another advantage is that .-;the -,circuit functions with very small capacitors, which results ,in a tremendous space saving.

While in the foregoingspecification embodiments .o'fithe invention .have been .set forth in considerable detail Ior purposes of providing an adequate disclosure thereof, it

, will be apparent that those skilled in the art ma make numerous changes therein without departing from th spirit .and principles of-the invention.

I claim:

In a circuit for detecting la change of predetermined character in a situation external thereof including '21 ,normally closed switch sensitive to such changes andbeing operative to open whenla change is sensed thereby, said circuit having a serially connected relay coil and .capaeitor in parallel withisaidswitc'h, 1a rectifier connected iiu parallel with said coil and with the input side thereof connected commonly with the switch and coil, a chargingresister for said capacitor and connected thereto, the point of connection between said switch, coil and rectifierbeing adapted to be connected to the positive side :of a direct current power supply which has the negative side thereof grounded, and circuit ouput means connected to the point of serial connection of said relay coil and capacitor, .11 pulse-forming network arranged within said circuit output means comprising a'rectifier having the input thereof connected to the output means of said circuit, serially connected resistance and capacitancee'lements havingthe free end of the resistance element connecte'dto the'output side of said secondmentioncd rectifier, said free end'being further coupled to the one side of the direct current power source, and having the free. end of said capacitance'element grounded.

References Cited in the tile of this patent UNITED STATES PATENTS Switzerland Sept. "16, 194-8 

